Method of making heat exchangers



METHOD OF MAKING HEAT EXCHANGERS Filed March 1, 1940 Inventor: Christian Steenstr'up,

Attorney.

Patented Mar. 31, 1942 UNITED STATE METHOD OF MAKING HEAT EXCHANGERS Christian Steenstrup, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application March 1, 1940, Serial No. 321,110 3 Claims. (01. 113-118) This invention relates to heat exchangers and more particularly to heat exchangers suitable for use as condensers in connection with refrigerating apparatus and it is an object of this invention to provide a novel heat exchanger conduit and a novel method of manufacturing heat exchangers provided with such conduits.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming, a part of this specification.

For a better understanding of my invention ref erenc may be had to the accompanying drawing in which Fig. l is a partial view of a heat exchanger formed according to my invention, and Fig. 2 is an enlarged perspective view illustrating a portion of a heat exchanger formed according to my invention and the method of assembly thereof.

Referring to the drawing, I have disclosed a heat exchanger lll including a plurality of heat transferring fins i I and a plurality of fluid conveying conduits or tubes 82 extending through suitable openings in the fins H. The tubes or fluid conveying conduits l2 are preferably formed from fiat sheet metal stock in strip form of relatively resilient material suitable for brazing, as'mild steel, for example, if copper is the brazing material, and are formed into members having the desired shape, tubular in the arrangement illustrated in the drawing, by a suitable forming operation, as by drawing through a suitable die. During the shaping operation the '35 strength than a butt joint and assures closer enstrips of metal are provided with flanges i3 exgagement between conduit and fin than with an tending longitudinally along opposite sides or overlapping joint. Moreover, the forming operaedges of the strips, the flanges being formed to tion need not be performed as accurately as in extend inwardly in the shaped form and lie adthe butt or overlapping typ seam. jacent each other at an angle to form a trough 40 After assembly, the heat exchanger is brazed or depression IS. A tube formed in this manner at a suitable temperature and in a suitable atis represented by the numeral H in Fig. 2. mosphere. Inasmuch as brazing is a well known The fins II are formed from relatively thin operation, full description thereof is believed unsheet material, preferably steel, and aperturedas necessary. However, I may coat the surfaces of indicated by the numeral l5 to receive the tubes 45 the collars l6 and the adjacent faces of the i2, Any suitable method may be used to form flanges I3 with copper oxide, for example, or pass the apertures l5, such as stamping, for example. a copper wire along the open seam indicated by The fins II are preferably formed with annular the numeral l1, inwhich case supplemental opencollars l6 about the perforations or openings l5. ings must be provided in communication with the The collars may be formed during the stamping 50 apertures I5 to permit passage of the wire. Capoperation why any other suitabl method. illary action will cause the molten brazing ma- For purposes of assembly, a plurality of fins terial to flow into the open seam for causing'the are disposed in parallel relationship with opencontacting flange faces to be brazed securely toings I5 aligned in any suitable way as by means 55 gether, and also to flow between the tubes and of a fixture or spacing members. Tubes l2 are then passed through the openings l5 as indicated in Fig.2, the openings l5 and collars I6 acting as dies forcing or moving the adjacent faces of the flanges I3 into clos engagement over substantially the entire area of the faces as indicated by the numeral I! in Fig. 2. Tube He in Fig. 2 illustrates a tube in its assembled form. It will be seen that the flanges l3 have been pressed. close- 'ly together over the full length of the tube and the above-mentioned trough has been reduced considerably. From the above description it will be apparent that the opening l5 should be smaller than the outside diameter of the preformed tube I4 and, in fact, should be of such a size as to press the adjacent faces of the flanges l3 into close engagement on passage through the openings l5.

In order to utilize the relative resiliency of the conduit material for maintaining the conduits in position with respect to fins II and assuring good contact between conduits and fins as well as along the seam preceding and during the brazing operaing to urge and maintain the walls of the tube in intimate thermal association with the material adjacent the opening in the fln, that is, into engagement with the collars I6. The large conthe collars IS in contact therewith for causing the adjoining surfaces to be brazed securely to- I gether.

While I have shown a particular embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of making a heat exchanger comprising the steps of shaping a strip of relatively resilient sheet metal into substantially the extending longitudinally along opposite edges thereof and at an angle with respect to each other, said flanges being adjacent each other and engaging each other adjacent th marginal edges thereof thereby forming a trough, placing perfo- 1 rated fins over the tube, the perforations being of a size to reduce the trough and force the adjacent faces of the flanges closely together to form an open seam, the relative resiliency of the material from which the fins are formed serving to urge the tube into engagement with the edges of the perforations, placing brazing material in the open seam and subjecting the assembly to heat for brazing the flanges together and the fins to the tubes.

2. The method of making a heat exchanger comprising the steps of shaping a strip of relatively resilient sheet metal into substantially the ultimately desired form with inturned flanges. extending longitudinally along opposite edges thereof and at an angle with respect to each other, said flanges being adjacent each other and engaging each other adjacent the marginal edges thereof thereby forming a trough, placing perfoultimately desired form with inturned flanges rated fins over the tube, the perforations being of a size to reduc the trough and force the adjacent faces of the flanges closely together to form an open seam, the relative resiliency of the material from which the flns are formed serving to urge the tub into engagement with the edges of the perforations, and securing said flanges together in fluid-tight relationship.

3. The method of making a heat exchanger comprising the steps of shaping a strip of relatively resilient sheet metal into substantially the ultimately desired form with inturned flanges exwith the edges of the perforations, and securing said flanges together in fluid-tight relationship.

CHRISTIAN STEENSTRUP. 

